Rust inhibiting lubricating oil compositions



United States Patent RUST lNI-IIBITIN G LUBRICATING OIL COMPOSITIONS Troy L. Cantrell, Drexel Hill, Pa., and John G. Peters, Audubon, N. J., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Application May 13, 1954, Serial No. 429,686

1 Claim. (Cl. 252-325) This invention relates to rust inhibiting lubricating oil compositions, and more particularly to lubricating oil compositions of this kind which contain small concentrations of each of (a) a dimer acid derived from an unsaturated fatty acid containing from 6 to 22 carbon atoms and from 2 to 3 ethylenic linkages per molecule, and (b) an alkyl ammonium dialkyl orthophosphate..

Commercial lubricating oils, particular-1y those which are required to function in the presence of water, such as turbine oils and paper machinery lubricating oils, should possess rust inhibiting characteristics not only while fresh, but also after aging or long periods of service, i. e., after protracted contact of the oil with oxygen at high, oxidizing temperatures.

Dimerized unsaturated fatty acids, or dimer acids, are only moderately effective as rust inhibitors in fresh lubricating oils, i. e., lubricating oils which have not been aged in the manner indicated. Quite surprisingly, in view of the relative ineffectiveness of dimer acids as 111st inhibitors in fresh lubricating oils, we have 'found that dimer acids are highly effective rust inhibitors in aged lubricating oils.

Since many known rust inhibitors are effective only in fresh oils and are incapable ofproviding the necessary protection to aged lubricating oils, except perhaps in very high concentrations, the discovery of the rust inhibiting characteristics of dimer acids in aged lubricating oils is important. Nevertheless, the use of dimer acids to impart rust inhibiting properties to commercial lubricating oils while fresh and after aging is somewhat impractical, since undesirably large concentrations of the dimer acids are required to achieve this objective.

We have found that lubricating oil compositions possessing rust preventive properties both while fresh and after aging can be obtained with the use of small, practical additive concentrations by incorporating in the base oil minute amounts of a combination of a dimer acid and an alkyl ammonium dialkyl orthophosphate. The invention specifically includes lubricating oils containing from 0.005 to 0.1 percent by weight of the composition of each of (a) a dimer acid derived from an unsaturated fatty acid containing from .6 to 22 carbon atoms and from 2 to 3 ethylenic linkages per molecule, and (b) an alkyl ammonium dialkyl orthophosphate whose N-alkyl group contains from 8 to 18 carbon atoms, and whose remaining alkyl groups contain from 3 to 10 carbon atoms. In a preferred embodiment, the rust preventive lubricating oil contains the concentrations indicated above of (a) a dimer of linoleic acid, and (b) lauryl ammonium,3- methylbutyLZ-ethylhexyl orthophosphate.

Commercial lubricating oils often contain, in addition to rust inhibitors, anti-oxidants, such as 2,6,di-t-butyl-4- methylphenol, silicone foam inhibitors, pour point depressors, viscosity and viscosity index improvers, de-

2,773,032 rammed Dec. 4, 1956 tergents, dyes, sludge inhibitors, and the like. Such improvement agents may be used without detriment in conjunction with the rust inhibitors of the herein disclosed lubricating oil compositions, and the use of such improvement agents is specifically included by the invention.

Lubricating oils which form suitable base oils for the herein disclosed oil compositions include lubricating oils not only of the parafiinic type but also of the naphthenic type, which oils may have been refined by solvent treatment, acid treatment, aluminum chloride treatment, or other conventional refining treatments. The invention is especially valuable in connection with highly refined parafiinic lubricating oils such as are obtained, for

eaxmple, by aluminum chloride treatment of paraflinic lubricating distillates.

Briefly, the dimeracids utilized in the invention are dimers, i. e., bimolecular addition products of conjugated or unconjugateddienoic or trienoic fatty acids containing from 6 to 22 carbon atoms prior to dimerization. Dimeric acids derived from dienoic and trienoic fatty acids are known and can be prepared by conventional methods which form no part of this invention.

More particularly, dimerized acids included by this invention are prepared from dior trienoic fatty acids having the generic formula CnHZn-mCOOH, where n is an integer of from 5 to 21 andxis 3 or 5. As will-be evident, such monomeric acids contain from 6 to 22 carbon atoms and contain 2 or 3 ethylenic linkages as the ratio of carbon to hydrogen increases, i. e., as x increases from 3 to 5.

Dimerized acids corresponding to the bimolecular addition products of the foregoing monomeric acids include 7 those represented by the generic formula:

c-on I! where n is an integer of from 10 to 42 and where x is aneven integer of from 6 to 10. The dimer acids aretherefore dibasic or dicarboxylic acids having from 12 to 44 carbon atoms.

Representative members of the class of dimerized acids included by this invention aredimers of dienoic acids such as sorbic (hexadienoic), linoleic (octadecadienoic), humoceric (nonadecadienoic), and eicosinic (eicosadienoic) acids. Representative of dimeric'acids derived from trienoic acids are dimers of. linolenic and'eleostearic (octadecatrienoic) acids. Dimer acids derived from dienoic and trienoic acids containing from 16 to 22 carbon atoms, and especially those containing 18 carbon atoms and those containing conjugated ethylenic link ages, are preferred for reasons of economy of manufacture and the general excellence of compounded lubricating oils containing such acids.

it is not necessary that'both of the unsaturated fatty acid molecules of the bimolecular addition product be oil concentrates. 7 'sirable in order to facilitate "compounding of -the lubri- V inhibiting properties to the -fresh..oil.

eludes amine salts represented by the following generic formula:

a RNlHz: where R is a straight, or branched chain, alkyl radical containingfrom-8 to 1'8icarbon atoms, and the R-ISllbStlfil cuts are 'alkyl radicals containings from 3 to carbon atoms.

Salts of the above-described class are formed by neucants for'l952 and 1947, respectively. Briefly, the dis- 7 tilled water version of ASTM test D665.'52 T, i. e.,

Prodecure A, involves immersion of a standard steel test.

rod for 24 hours inanagitated mixture of distilled water and test oil maintained at a temperature of 140 F. The corrosion inhibiting properties of the still fresh, or non-aged, oil are evaluated by examination of the steel rod for corrosion or rust upon completion of the test. ASTM D 943-47T is carried out by passing oxygen at 'a measured rate of 3 liters per hour into an oilrwater.

mixture maintained at 203 :and having an iron coil.v immersed .therein.- According to the procedure followed V herein, the test was carried .out for 500 hours. The-corbelow 180 F; inorder to avoid appreciable decomposition of the alkyl' amine saltreactionproduct. The reaction is normally complete in less than rninutes.

Representative examples of specific alkyl ammonium dialkyl orthophosphates included 'by the inventionfare octyl, decyL-dodecyl, tetradecyl and octadecyl ammonium di ropyLdi-n-amy'l, diisoamyl', -di=n-'octyl, diisoocytl, isoamyl, isooctyl, and "di-n-capryl orthophosphates.

The individual rust inhibitors "o f'this invention'may be added to the lubricating oil "base in" either order or simultaneously, either per -se, or in the form of mineral The latter practice is sometimes decating oil I a v As indicated, each of the rust inhibitors included 'by this invention may be employed inthe lubricating oil composition in an amountranging from 0.005 to 0.1-

' percent by weight of the composition.

respective rust inhibitors are utilized in the composition in a weight ratio of between about 1:3 to about 3:1.

rosion inhibiting properties. of gthe ;aged oil were deter.- mined by examination of the iron :coil during and after the test for .rust or corrosion. The amount of rust on :the coil was recorded. as none, trace, light, medium, or

heavy, the term trace being used to designate the slightest'fleck of rust. I v a The base oil used in-the testswas a highly refined, aluminum chloride treated, paraflinic turbineoil stock having an A'Pl gravity'of 'between BOES? and 325 and a viscosity of about ISO SUS at 1.00 'andlcontaining 1.25'percerit by weight of 2,6,di t butyl-4,methylphenol as an anti-oxidant and OLOO33 -percent by weight of the composition of Dow Corning silicone Fluid 200 as a foam inhibitor.

Separate samples of the above-described base oil were made up containing, respectively: '0' percent rust inhibitors, 0.04, 0:05, and 0.2 percent dimerized linoleic acid, 0.04 percent lauryl ammonium-3-methylbutyl, V Z-et'hylhexyl orthophospha-te, and a combination of. 0.016 percent by weight of lauryl ammonium, 3-rnethyl-butyl, .2-ethylhexyl orthophospha-te and 0:024'percn't'by weight of the dimerized linoleic acid. The respective oil samples were tested for corrosion inhibiting properties both in fresh condition andafter aging by subjecting them to the Desirably the Concentrations of the herein disclosed rust inhibitors v, within the foregoing range are suflicient to impart outstanding corrosion inhibiting properties to lubricating oil-compositions both a fresh condition :and after 7 extensive gpeniods 'of aging. during 'seniice. 16f course, the specific required concentrations of each individual inhibitor may vary somewhat, both according :to thefna- V ture of the base oil and according to thexcon'ditions to which the oilis'subjected. It is an important advantage of the invention that 'rust'zinhibiting characteristics may be imparted to ;the oil in both'sfresh andcaged condition with the use of a lower concentration -c.of :dimer a cid, sand with the use of a lower total rust inhibitor concentration, than the dimer acidconcentrationnormallyzrequired I to produce these results; Moreover, :since the dimer acid contributes to rust inhibition tin the :fresh oil, the con- 7 centration of the orthophosphate in the composition may Y .also be below that normally. required zto impart rust 'oils so tested with similarly testedllibricating 'oils of different composition. I The foregoing standard testsaredescribed in detail in the ASTM Standards of Petroleum"P-roduc'ts and Lubriabove-described test procedures. The results obtained from the foregoing tests are indicated by the following Composition 1 in the foregoing'table is representative of the characteristics of the'uninhibitedoils Oomposi- .tions 2, 3 and 4 demonstrate the large concentrationof dimer acid required for efiec-tive results :in fresh oils.

o-phosphate alone is ineffective to impart rust preventive j properties to aged oils. Composition fi in the foregoing table is illustrative of thecompos-itions of this-invention.

' This composition possessed highly-effective rust-preventive properties both while fresh and'lafter aging, notwithstanding the .use of a concentration of dimeracid much lower than thatirequired to provide effective rustrpreventive-propertiesin fresh and aged oils, and notwithstanding theruse of a concentration .of llauryl za-mmoniurn, 3 V I *methylbutyl, Z-ethylhexyl o-phosph ate lo wer than the normal minimum required to impartrus-t preventive proper- I ties to a fresh oil of the kind used 'inythe tests. Our com position thus achieves effective rust protection for fresh and aged oils-with a-minimum total additive concentration. Other.'rustpreventive lubricating oils, possessing similar advantages, can be compounded, using other additive combinations selected from the disclosed classes.

It is understood that many modifications of the herein disclosed invention may be resorted to without departing from the spirit or scope thereof. Accordingly, we intend to be limited only by the scope of the claim appended hereto.

We claim:

A composition comprising a major amount of a mineral lubricating oil, and about 0.024 percent by weight of the composition of dimerized linoleic acid, and about 0.016 percent by weight of the composition of a salt of a primary alkyl amine containing 8 to 18 carbon atoms per molecule and 3-methylbutyl, 2- ethylhexyl orthophosphate.

References Cited in the file of this patent UNITED STATES PATENTS 

